<template>
    <div>
        <p>请选择你要购买的书籍</p>
        <ul>
            <li v-for="(item,index) in arr " :key="index">
                {{item.name}}
                <button @click="btn(index)">买书</button>
            </li>
        </ul>
        <table border="1" width="500" cellspacing="0">
            <tr>
                <th>序号</th>
                <th>书名</th>
                <th>单价</th>
                <th>数量</th>
                <th>合计</th>
            </tr>
            <tr v-for="(obj,index) in arr" :key="index">
                <td>{{index+1}}</td>
                <td>{{obj.name}}</td>
                <td>{{obj.price}}</td>
                <td>{{obj.count}}</td>
                <td>{{obj.price*obj.count}}</td>

            </tr>
        </table>
        <p>总价格为:{{zj}} </p>
    </div>
</template>

<script>
    export default {
        data() {
            return {
                arr: [{
                        name: "水浒传",
                        price: 107,
                        count: 0,
                    },
                    {
                        name: "西游记",
                        price: 192,
                        count: 0,
                    },
                    {
                        name: "三国演义",
                        price: 219,
                        count: 0,
                    },
                    {
                        name: "红楼梦",
                        price: 178,
                        count: 0,
                    },
                ],
            };
        },
        methods: {
            btn(index) {
                this.arr[index]["count"]++
            }
        },
        computed: {
            zj() {
                return this.arr.reduce((sum, obj) => {
                    return (sum += obj.price * obj.count)
                }, 0)
            }
        }
    };
</script>